Arrangement for generating voltages for aiming a gun

ABSTRACT

An arrangement for creating voltages for aiming a gun, such as for lateral correction or correction of the elevation of the gun making use of the similarity between the charging or discharging function of a capacitor in a series circuit comprising a resistor and a capacitor and the required correction as a function of the firing range of the gun.

United States Patent [72] Inventors Carl-ErlkGranqvist [54] ARRANGEMENT FOR GENERATING VOLTAGES FOR AIMING A GUN 5 Claims, 3 Drawing Figs.

[52} U.S. Cl 328/147,

[51] InLCI G06g 7/14 [50] Field ofSearch 328/147, 142,127, 156, 58; 307/235, 265, 230, 264; 89/41 L,41LE,41MC,41ME,41R

[ 1 References Cited UNITED STATES PATENTS 3.290.992 12/1966 Blomquist 9/41 71 E Primary ExaminerStanley T. Krawczewicz Attorney-Larson and Taylor ABSTRACT: An arrangement for creating voltages for aiming a gun, such as for lateral correction or correction of the elevation of the gun making use of the similarity between the charging or discharging function of a capacitor in a series circuit comprising a resistor and a capacitor and the required correction as a function of the firing range of the gun.

3 6 4 Q I4 Ux 7 ARRANGEMENT IFOR GENERATING VOLTAGES FOR AIMING A GUN BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arrangement for creating voltages for aiming a gun, such as for the required lateral correction owing to parallax between a range-finding instrument and a gun or for correcting the elevation of the gun in view of the influence of the ballistic properties of the projectile when firing on distances large enough to require that the curvature of the path of the projectile be taken into account.

2. Description of the Prior Art Such a calculation of the elevation of a gun is relatively complicated as it involves higher degree functions. Conventionally, firing tables have been used for calculating the elevation required for certain defined input data such as firing range, muzzle velocity of 'the projectile, air temperature and pressure. Another method of the prior art includes generating the nonlinear function with the aid of, for instance, curves, nonlinear potentiometers or function-generating networks of a relatively complex nature.

SUMMARY OF THE INVENTION The present invention is based on the similarity which is present between the discharge or charging function of a capacitor in a series circuit comprising a resistor and a capacitor on one hand and the required lateral correction or elevation as a function of the firing range on the other hand. According to the invention, there is generated an electric voltage representing the required lateral correction or the influence of the ballistic properties of a projectile on the elevation of the gun, a DC voltage, whose amplitude represents factors influencing the lateral correction or the ballistic properties, being adapted to be applied to a resistor-capacitor series circuit and the capacitor voltage being adapted to be compared in an operation amplifier with a DC voltage which is proportional to the firing range, whereby the duration of a pulse generated by said amplifier represents the said influence of the ballistic properties on the elevation.

BRIEF DESCRIPT ION OF THE DRAWING The invention will be described below with reference to the attached drawing, FIG. ll of which is a circuit diagram of essential circuit components of the arrangement, FIG. 2 shows graphs serving to explain the operation of the arrangement, and FIG. 3 is a modified form of the circuit of FIG. 1 adapted for generating a voltage representing the required lateral correction owing to parallax between a range-finding instrument and the gun.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The FIG. 1 circuit comprises a first series circuit of a resistor 1 and a capacitor 2 connected between a terminal 3 and a point of fixed potential, such as ground. Connected between terminal 3 and resistor l is a field effect transistor 4 serving as a relay. The conductivity of transistor 4 is controlled by a control voltage L,, which is applied via a tenninal 5 and a series resistor 6. The shape of the control voltage L, is shown in FIG. 2. It may comprise, for instance, the output voltage of a logical circuit alternating between the values zero and one.

The voltage U, which is applied to the terminal 3 is assumed to have an amplitude representing factors of importance for the ballistic properties. Such factors are the type of ammunition, the initial velocity of the projectile, air pressure, air tem- Before the application of the voltage U, which is present at terminal 3 to the series circuit of resistor l and capacitor 2 being brought about by the field effect transistor 4 when it is rendered conductive by the pulse L,, capacitor 2 has been discharged owing to the fact that a second control voltage L the shape which is shown in FIG. 2, has been applied via a terminal 7 and has rendered a second field effect transistor 8, which is connected in parallel to capacitor 2, conductive so as to discharge this capacitor. The control voltage L similarly to a control voltage L,, may comprise the output signal of a logical circuit and alternate between the values one and zero, it being noted that the voltage L, is the inversion of the voltage L Thus, after the initial discharging of capacitor 2, voltage U, is applied at time t=0 to the series circuit of resistor l and capacitor 2. The voltage across capacitor 2 then rises according to the graph U, of FIG. 2. Voltage U is applied via a first operational amplifier 9, whose operation will be described below, to a second operational amplifier 10, in which voltage U is adapted to be compared with a voltage U which is applied via a terminal 11. This latter voltage is assumed to be derived from a generator, whose output voltage is of an amplitude proportional to firing range. As is apparent from FIG. 2, voltage U,. across capacitor 2 has reached the value U at time t,. This means that there is supplied from operational amplifier 10 a pulse, designated U,,, in FIG. 2, the duration of which is 1,. This duration therefore represents the influence of ballistics on the elevation of the gun, as referred to in the introduction.

If it is desired to have a voltage whose amplitude represents the said influence, voltage U can be applied to an integrator 12, which may comprise in known manner an operational amplifier having a feedback via a capacitor 13. The output from this integrator, designated U in FIG. 2, will therefore rise linearly with time so as to reach at time t, the value shown in FIG. 2.

As is apparent from the above, there has been generated with the aid of the simple e function corresponding to the charging of a capacitor a voltage representing accurately the influence of ballistics on the elevation of a gun. If a higher degree of accuracy is required, a correction may be applied to this simple 2 function with the aid of an additional series circuit of resistor 14 and capacitor 15 having a second reference voltage U, applied to it. This voltage can be generated in known manner in the same way as the voltage U, and may represent further functions influencing the ballistic properties of the projectile.

Capacitor 15 is discharged before a measurement is started similarly to capacitor 2 with the aid of control voltage L, which acts on a field effect transistor 16 connected in parallel with capacitor 15. Voltage U is then applied in response to control voltage L, via a field effect transistor 17 to series circuit l4, 15. The voltage across capacitor 15 is then applied together with the output across capacitor 2 to the operation amplifier 9, the output of which will therefore represent the combined influence of voltages U, and U,.

There has been described above an arrangement for generating a voltage representing the influence of the ballistic properties of a projectile. If it is desired to create a voltage representing the required lateral correction owing to parallax between a range-finding instrument and the gun, it is possible to use a modification of the FIG. 1 arrangement, in which the control voltage L, does not imitate discharging of a capacitor but instead charges it to a predetermined initial voltage. Furthermore, the capacitor is made to discharge through a resistor when control voltage L, is applied to the arrangement. The discharge then takes place according to an 2 function and perature and the temperature of the gun powder. This voltage after a certain time 10- p n ing 10 the d an can be generated in known manner with the aid of an operation amplifier, to the input of which there are applied DC voltages, each of which is proportional to the said factors, there being obtained from the output circuit of the operation amplifier the desired output voltage U,.

between the gun and the target, the capacitor is disconnected from the discharging circuit. The remaining voltage of the capacitor then represents the lateral correction required for a certain firing range owing to the parallax between the rangefinding instrument and the gun.

An example of a circuit comprising a series connection of resistor and capacitor for generating the function just referred to is shown in FIG. 3. With the aid of a control voltage L a field effect transistor 8 can be rendered conductive, whereby capacitor 2 is instantly charged to voltage U,. Control voltage L then renders a second field effect transistor 4' conductive and initiates the discharge of capacitor 2' through resistor l in accordance with the graph U, as is indicated in F IG. 2 by a dash line. At the time t the discharging of the capacitor 2 stops for instance by interrupting the control voltage L and the voltage then present at the capacitor represents the necessary lateral correction and can be used for aiming the gun in a manner known in the art.

We claim:

1. An electrical circuit for producing an electrical control signal for controlling the aiming of a gun at a target lying at a certain range comprising an ohmic resistor, a capacitor, means for connecting said resistor and said capacitor in a series circuit, switching means for selectively connecting said series circuit to a source of DC voltage of an amplitude representative of at least one factor related to the range of the gun, an operational amplifier having first and second inputs, means for connecting a point on the series connection between said resistor and said capacitor to said first input of said operational amplifier, and means for connecting said second input to said operational amplifier to a source of voltage representative of the range of the target so that said operational amplifier produces a pulse the duration of which is related to the required correction of the aiming of the gun in accordance with the at least one factor.

2. A circuit as claimed in claim 1 further comprising an integrator connected to the output of said operational amplifier for producing a voltage of an amplitude proportional to the duration of said pulse.

3. A circuit as claimed in claim 1 further comprising a further capacitor, a further resistor, means for connecting said further capacitor and further resistor in series, a further operational amplifier, means for connecting a point on the series connection between said further capacitor and said further resistor to a first input of said further operational amplifier, means for connecting said point on the series connection between the first-mentioned resistor and the first-mentioned capacitor to said first input of said further operational amplifier and means for connecting the output of said further operational amplifier to said first input to the first-mentioned operational amplifier.

4. A circuit as claimed in claim 3 wherein the series combination of said further resistor and said further capacitor are connected to a further source of DC voltage of an amplitude proportional to a further factor related to the range of said gun.

5. An electrical circuit for producing an electrical control signal representative of the lateral correction in the aiming of a gun required due to parallax between the gun and a rangefinding instrument comprising a capacitor, means for connecting the capacitor to a DC voltage of an amplitude proportional to the distance between the gun and the range finder instrument, a resistor connected to the capacitor to provide a discharge path therefor, and switching means for interrupting the discharge of said capacitor after a time corresponding to the distance between the gun and the target at which the gun is aimed such that the voltage on the capacitor at the time of interruption of the discharge thereof is representative of the lateral correction required for the parallax between the gun and the range-finding instrument for that range. 

1. An electrical circuit for producing an electrical control signal for controlling the aiming of a gun at a target lying at a certain range comprising an ohmic resistor, a capacitor, means for connecting said resistor and said capacitor in a series circuit, switching means for selectively connecting said series circuit to a source of DC voltage of an amplitude representative of at least one factor related to the range of the gun, an operational amplifier having first and second inputs, means for connecting a point on the series connection between said resistor and said capacitor to said first input of said operational amplifier, and means for connecting said second input to said operational amplifier to a source of voltage representative of the range of the target so that said operational amplifier produces a pulse the duration of which is related to the required correction of the aiming of the gun in accordance with the at least one factor.
 2. A circuit as claimed in claim 1 further comprising an integrator connected to the output of said operational amplifier for producing a voltage of an amplitude proportional to the duration of said pulse.
 3. A circuit as claimed in claim 1 further comprising a further capacitor, a further resistor, means for connecting said further capacitor and further resistor in series, a further operational amplifier, means for connecting a point on the series connection between said further capacitor and said further resistor to a first input of said further operational amplifier, means for connecting said point on the series connection between the first-mentioned resistor and the first-mentioned capacitor to said first input of said further operational amplifier and means for connecting the output of said further operational amplifier to said first input to the first-mentioned operational amplifier.
 4. A ciRcuit as claimed in claim 3 wherein the series combination of said further resistor and said further capacitor are connected to a further source of DC voltage of an amplitude proportional to a further factor related to the range of said gun.
 5. An electrical circuit for producing an electrical control signal representative of the lateral correction in the aiming of a gun required due to parallax between the gun and a range-finding instrument comprising a capacitor, means for connecting the capacitor to a DC voltage of an amplitude proportional to the distance between the gun and the range finder instrument, a resistor connected to the capacitor to provide a discharge path therefor, and switching means for interrupting the discharge of said capacitor after a time corresponding to the distance between the gun and the target at which the gun is aimed such that the voltage on the capacitor at the time of interruption of the discharge thereof is representative of the lateral correction required for the parallax between the gun and the range-finding instrument for that range. 